Not saying solar activity couldn't be a contributing factor, but something else was at least marginal first...
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voretaq7♦Jun 9 '11 at 16:07

1

@milkmood I would start looking for other things that the printers have in common (like being on the same network). Please remember, that although "solar flare" may be a good overall excuse it VERY rarely is the real cause.
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João PortelaJun 9 '11 at 17:37

While it is theoretically possible for solar events to affect electronics, the probability is very small for printers, especially two printers in the same area. Bianca Schroeder worked with Google to do a full scale study of the number of DRAM errors caused by cosmic rays and other atmospheric phenomenon and found an incidence rate of between 25,000 to 70,000 errors per billion device hours per Mbit. She also found that 8.2% of DIMMs had errors per device year. (“DRAM Errors in the Wild: A Large-Scale Field Study”, Bianca Schroeder, Eduardo Pinheiro, Wolf-Dietrich Weber, SIGMETRICS, 2009.)

Taking the worst-case scenarios: that the first error is catastrophic, that your printer has around 16M of RAM in it and is using one of the older technologies, and doing some fairly aggressive back of the envelope math, the probability of two printers failing at the same time during a high-activity cosmic event is equal to:
where p = 1/100000 and n = 5.

Long story short, the probability is vanishingly small - like, earth spontaneously turning into a goldfish small.

Edit: I think I spent way too long on this. Simple answer would have sufficed.

I didn't say any such thing - I said you were grasping at straws, which you are. Gallileo spent his life doing experiments to reach his insights, I think you flatter yourself to the point of ridicule by comparing yourself him!
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Bart BJun 9 '11 at 15:53